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101.
Eucalyptus forest; and in the composition of understorey herbs, sedges, and grasslands. Pollen concentration and charcoal and organic content also exhibit post-European changes. Thus, pollen analysis provides a technique for determining changes in sediment budgets and identifying major vegetation changes in floodplains. 相似文献
102.
This study quantifies the disruption of zooplankton population fluctuations in relation to two magnitudes of fire retardant contamination events using artificial ponds as model systems. Population time series were analysed using redundancy analysis where time was modelled with a principal coordinate of neighborhood matrices approach that identified relevant scales of fluctuation frequencies. Analyses of temporal coherence provided insight whether population fluctuations correlated with system intrinsic or extrinsic forces. Responses to stress were species-specific and context-dependant. Contamination changed temporal structure in some species. These alterations were associated with an increased intrinsic control of dynamics. In some cases the magnitude of impact was unrelated to contamination severity. Some populations were less tolerant of pollution in the low relative to the high concentration treatment. Results suggest that population-level monitoring of degraded sites may be suboptimal because disparate population responses complicate the selection of specific sentinel organisms to monitor stress. 相似文献
103.
Fire as a Soil-Forming Factor 总被引:2,自引:0,他引:2
Giacomo Certini 《Ambio》2014,43(2):191-195
In the span of a human generation, fire can, in theory, impact all the land covered by vegetation. Its occurrence has many important direct and indirect effects on soil, some of which are long-lasting or even permanent. As a consequence, fire must be considered a soil-forming factor, on par with the others traditionally recognized, namely: parent material, topography, time, climate, living beings not endowed with the power of reason, and humans. 相似文献
104.
105.
本文研究了空心玻璃微珠添加量及泡沫液浓度对泡沫灭火剂发泡能力和稳定性的影响,对比了热辐射条件下空心玻璃微珠添加前后泡沫的热稳定性.结果表明,添加量低于40%时,空心玻璃微珠对泡沫灭火剂发泡能力影响不大,而泡沫的稳定性显著降低,添加量为50%时,虽泡沫发泡能力降低,但泡沫的稳定性却增强.泡沫的发泡能力随蛋白泡沫浓度升高而增强.蛋白浓度为10%,空心微珠添加量为50%时,由于泡沫内部形成了稳定的三相泡沫骨架结构,泡沫热稳定性较未添加微珠之前显著增强. 相似文献
106.
To overcome the shortcomings of phosphorus-containing compounds (PCCs, not widely used) in fire suppression, the dry water powder containing phosphoric acid was analyzed for a new fire suppressant (SiO2-P). First, the fine conditions (solid-to-liquid ratio, stirring time and stirring speed) were determined to prepare the new powder. The particle size distributions and XPS of SiO2-P powder were analyzed. The TG tests were conducted to study the decomposition of powder, and there was a major decomposition peak. Second, the extinguishing time of SiO2-P powder was tested, which showed that the SiO2-P powder containing phosphorus species could significantly improve the fire suppression ability. In addition, the kinetic parameters of powder decomposition reaction were determined by genetic algorithm based on TG results. Last, based on the decomposition products and kinetic parameters, the burning velocity and mass fraction of free radicals of CH4/air flame with SiO2-P powder addition were studied theoretically. The results indicated that SiO2-P powder had great ability of reducing the burning velocity and scavenging free radicals. Furthermore, the suppression effects were analyzed, which indicated that the cooperation of H2O and P suppression effect dominated the suppression mechanism and resulted in the good suppression efficiency. 相似文献
107.
对丙烯腈、醋酸乙酯罐系统危险性及罐区泄漏潜在危险性进行了系统分析。并对丙烯腈、醋酸乙烯酯罐区的防火防爆提出了相应的对策,对泡沫消防设备及可燃气体检测器灭火系统的可行性和实用性进行了重点介绍和探讨。 相似文献
108.
烟草行业的火灾特点及其监测方法的讨论 总被引:1,自引:0,他引:1
烟厂是火灾危险性较大的部门,加强其火灾的早期探测报警是防止火灾发生、减少火灾损失的重要方面。本文对烟厂中各主要生产环节的火灾特点作了分析,指出应针对各部分的特殊性采取适当的火灾探测方法并对现在常用的一些火灾探测技术在烟厂中的适用性作了讨论,认为现有的光束式火灾探测器较适用于内部空间较大的烟厂仓库和厂房。对安装了电视监控系统的企业,建议将其与计算机图象分析技术相结合,增加其防火监视功能。 相似文献
109.
井下火花——矿井火灾的点燃源 总被引:1,自引:0,他引:1
考察了各类井下火花诱发灾害的典型实例以及80年代以来国内外的研究状况,指出深入开展这一课题的研究对防灾的重要性. 相似文献
110.
建立了人、机、大气环境扰动的动力学模型。形成一个便于仿真计算的人-机-环境系统模型,针对驾驶员完成俯仰跟踪任务,研究了大气扰动对驾驶员控制特性和人-机闭环特性的影响。 相似文献